


AlBr3

by RandomExtra



Category: Haikyuu!!
Genre: Akaashi Keiji Is So Done, Alchemist Kuroo Tetsurou, Alternate Universe - Fantasy, Alternate Universe - Magic, Alternate Universe - Royalty, Bokuto Koutarou & Kuroo Tetsurou Friendship, Bokuto Koutarou Being Bokuto Koutarou, Chemistry, Friends to Lovers, Idiots in Love, Kozume Kenma & Kuroo Tetsurou Friendship, Kuroo Tetsurou is a Mess, M/M, Mage Kozume Kenma, Mentioned Kozume Kenma, Mutual Pining, Not Beta Read, Oblivious Bokuto Koutarou, Pining Bokuto Koutarou, Pining Kuroo Tetsurou, Prince Bokuto Koutarou, Royal Advisor Akaashi Keiji, Science Experiments, kind of?
Language: English
Status: Completed
Published: 2021-02-19
Updated: 2021-02-19
Packaged: 2021-03-16 05:13:47
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,440
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29201904
Author URL: https://archiveofourown.org/users/RandomExtra/pseuds/RandomExtra
Summary: A flash of messy raven hair popped up from behind the large forge across from the door and a heavy face shield was lifted to reveal a scowling face. He looked exasperated, but his eyes shone with a bit of fond mischief.The Castle’s resident Alchemist…“Seriously man, you can’t keep barging in here, what if I’d been in the middle of an experiment?”...And the crown prince’s best friend:“Kuroo!” He yelled, marching up to the tables and leveling his friend with a stare, his advisor walking in behind him, albeit more carefully, “You have to help me, look at my sword!” He thrust the weapon out in front of him, it coming close enough for Kuroo to swat at his arm to make him move it back a bit.Once he could actually see it he let out a low whistle.“Whoa, the hell’d you do Bo?”
Relationships: Bokuto Koutarou & Kuroo Tetsurou, Bokuto Koutarou/Kuroo Tetsurou
Comments: 2
Kudos: 31





	AlBr3

**Author's Note:**

> Hi, I am just a little obsessed with Kuroo so expect more of him in the future lol (also pls ignore the fact that they use some science terms too advanced for the time period thanks XD)

**-CRASH-**

The doors flew open, letting the light from the adjoining courtyard stream in exposing the cluttered space. 

It was lit by a few torches scattered throughout, and one large window forming a dome at the top of the building. Pulleys and long ropes and chains fell from the ceiling attaching strange mechanisms labeled by fraying colored pieces of cloth, marred by symbols stitched into them. The supposedly organized mess was only really understood by the man who ran it. 

In the center, there was a large hole in the ground used to mix larger quantities and three tables on a raised level, covered with papers and books and other materials written in languages most assumed to be completely forgotten. 

Towards the top, there were mantels filled with stacks and stacks of heavy books that he couldn’t be bothered to read. They were accessible by tall spindly steps that went up to the top and sliding ladders that almost gave the attendants heart attacks when the lanky man carelessly made his way through the space 

The shelves below were lined with flasks and jars filled with unknown substances. Some glittered like the brightest diamonds but could give off enough energy to make the ground shake. Others gave off a spooky luminescent glow like evil jellyfish but could be used as paint on their lanterns. It was impossible to tell, so it was best for everyone not to touch anything without permission. He’d definitely learned that the hard way after many,  _ many  _ accidents. 

Endless scoldings had only done so much.

A flash of messy raven hair popped up from behind the large forge across from the door and a heavy face shield was lifted to reveal a scowling face. He looked exasperated, but his eyes shone with a bit of fond mischief. 

The Castle’s resident Alchemist…

“Seriously man, you can’t keep barging in here, what if I’d been in the middle of an experiment?”

...And the crown prince’s best friend: 

“Kuroo!” He yelled, marching up to the tables and leveling his friend with a stare, his advisor walking in behind him, albeit more carefully, “You have to help me, look at my sword!” He thrust the weapon out in front of him, it coming close enough for Kuroo to swat at his arm to make him move it back a bit. 

Once he could actually see it he let out a low whistle. 

“Whoa, the hell’d you do Bo?” 

The blade was covered from guard to point in a gloopy, silver solid. He traced it with his fingers and they came back dry. The surface was cool to the touch, but just by the uneven surface, he could tell that it was a thick and thoroughly hardened coating. 

“We were working outside the borders and we fell into a weird cave thing, someone got stuck under some rocks so I used my sword to cut through them, but it came back all messed up,” He explained, Akaashi nodding silently behind him. Kuroo looked between them and the sword, his eyebrows rising to disappear beneath the band of his guard. 

“No offense bro, but I’m no weapons master and it’s not my job to clean your shit so uh, find a chisel and start scraping,” Kuroo said, before turning to pick up one of his books. Bokuto’s hand caught his elbow.

“I already tried that, if I do it’s gonna damage the blade,” 

“Well, that sucks and I’m sorry, but I don’t know what you want me to do about it?” He asked, shooting him a quizzical look. 

“Can’t you use your magic to get rid of it? Please?” Bokuto’s eyes were pleading and Kuroo had to force himself to look away, he was way weaker to that face than he’d like to admit. 

“S’not magic and Bo, you know I’d love to help you, but the head of the guard needs these elixirs done today and-”

“Please, Tetsu, it’s my dad’s I promised I’d take care of it,” His tone was desperate and his gaze was boring into Kuroo’s as he tugged him towards him. With the stumble pulling his stare up to make eye contact, his resolve was shaken, and he had no choice, but to give in to those golden eyes, as he usually did. He could practically feel Akaashi’s knowing stare aimed at the back of his head. 

Damnit. Why’d the prince have to be so bright?

He sighed and looked down at the tarnished sword again, the wheels in his head beginning to turn as he took a second look. 

“What’s it made of?” Kuroo asked, as he carefully grabbed a small tool and delicately chipped off a piece of the substance without breaching the lower layer and risking damage to the blade itself. He traded one tool for another on his belt and as he took in the magnified view, Bokuto’s eyes roamed over his lean form. 

He was in his normal dark clothes with his belt lined with pouches, filled with potions, ingredients, and other useful things. His sleeves were rolled up to his elbows and there was a pencil tucked behind his ear. Ash and dirt covered his boots and even managed to smudge onto his cheek as usual. The sweat slipping down his face as he screwed his eyes up in concentration was a serious distraction. 

“Huh?” 

“The blade, what’s it made of?” Kuroo asked, giving him an expectant look as he set the sample down, an idea forming in his head as he took the sword from his friend’s open hands. 

“Um, steel I think?” Bokuto tried. It came out as more of a question as he turned to Akaashi who nodded. 

“Anything else?” Kuroo was turning to his shelves now, picking up his heaviest pair of gloves and slipping them on. He climbed up one of the ladders and released the chains to one of the long, cylindrical clear metal tubes. After steadying it, he set the sword aside.

“Titanium,” Akaashi added, earning a nod from the taller man as he passed by them again to go to the other side of the room. He turned a knob and a cabinet swung open, exposing a large jar made of thick glass containing a strange red liquid. He lifted it off the shelf and cautiously carried it over to the hole, setting down on the side, not opening it yet. 

“Good, that means it might hold its shape,” he muttered, making Bokuto prick up in alarm. 

“What?”

“Okay,” He said, turning back to them and motioning towards the space behind them, “Those boxes have some goggles in them, both of you put them on and stand by the door,” The man turned on his heel and strolled over to the pit again, grabbing the sword and climbing up the side of the hole to stand on the edge beside the jar.

“What’re you gonna do?” the prince asked, eying the seemingly precarious position of everything in unveiled suspicion. Kuroo chuckled from his place, fiddling with a pipeline above head so that the end of it angled to let out into the tube. 

He dropped down onto the edge again and leaned down to pick up the jar. 

“This is Bromine,” Kuroo stated, taking a step towards the tube, before stopping to kick a lever on the wall. This sent a large see-through screen up in front of the other two boys who jumped back in surprise, “It’s highly corrosive and very reactive,”

“Wait, doesn’t that mean it’ll just destroy the sword?” Akaashi asked, concern beginning to lace his tone. 

Kuroo smiled wickedly and Bokuto shivered as popped the cap and poured the red liquid into the tube.

It coated the walls of it before gathering at the bottom in a thick pool, coming up to about a fifth of the way up, but the yellow-orange gas that followed it filling the rest to the brim, but not spilling over the sides. Kuroo unraveled a crank from his place on the wall, grabbing the hook that came down from the ceiling and attaching the sword to it after covering the hilt in some sort of protective thick glass. He recranked it to a good height and stood up, his free hand coming up to rest on his protective headgear. 

“Not if I cool it off fast enough,” He simpered, before flipping the shield down over his face and letting the sword down into the liquid. 

Then quickly jumping down off of the wall and scurrying over to the ladders, he barely managed to get himself out of the range when the reaction began. 

The Bromine began to travel up the sword, painting the strange layer in maroon. Then it began to spark, sending swirling lines of golden light, orbiting the sword in rapid circles, scraping the walls as they went. Once they reached the top they erupted in brilliant orange, sending glinting flecks on a peculiar white stone into the air and releasing clouds of orange-tinged smoke as it did. Then the fire really took and its radiant glow seemed to reverberate throughout the room as the flecks came out at a more lively speed, dancing through the air like molten fireflies dipping down in curiosity to taste the cold stone floor. 

Behind the glass in the face shield, Bokuto could see the man’s amber eyes glowing in the light and he couldn’t help the small awed sound that came from him. Judging by the way Akaashi’s posture had dropped from its usual stiffness and his air of perfection had been breached by the slack of his jaw, he was in a similar state. 

“H-how did you-? What’s it doing?” Bokuto stuttered, too enraptured to care how undignified he must look and sound. Kuroo laughed from the other side of the room.

“It’s eating through the weird layer and letting it out in those pieces of rock,” He yelled over the loud crackling sound. 

“Why is it burning like that then?” Akaashi asked, not pulling his eyes away from the cylinder. 

“I told you it was highly reactive right? This is one of the reactions,” He responded, getting down off the ladder as the flecks began to come slower and stop shooting out at such a large radius, containing themselves to the walled-in hole now, “Far more intense than I expected, but hey it’s working right?”

Bokuto laughed boisterously at that, and even Akaashi let a small smile grace his features. The prince could feel Kuroo’s grin despite the guard blocking his view, and it only seemed to grow as he reached up to grab at a chain marked with blue cloth, worn with age and covered in dirt, so it almost appeared to be gray. 

He tugged on it and a creak sounded. Then silence. Kuroo tried it again, using more force this time, but got the same result. He let out a string of curses that would make even his mage friend Kenma make a face and looked up at the chain, eyes searching for something. 

“Kuroo, what’s wrong, what’s happening?” The Prince shouted looking between the man and the tube in steadily growing alarm. The fire had begun to blaze even brighter, the form of the sword inside of it begging to glow a dull red like it was made of magma that was awaking from a long period of inactivity. 

The only answer he received was a shout of “Stay there,” before the man jumped onto one of the ladders and kicked off, sending it careening towards the wall that held the forge. Just as it was about to ram into the wall, sending both the ladder and the alchemist flying, the man used the built-up momentum to throw himself up and over, grabbing onto the chains with a loud rattle and suspending him into the air by only his grip strength. Bokuto would be impressed if wasn’t having a minor heart attack watching him climb up the chains above the increasingly more dangerous fire. 

He pulled himself all the way up until he disappeared through the slight gap in the planks and the mess of chains into the top level. 

That was the weird thing about the tower that they were in, it was part lab, part observatory. Only Kuroo was allowed up, so no one knew what it really looked like, and from what he’d heard, it was strange and messy, but also gave a brilliant view of the unobstructed night sky from the highest point in the whole sky kingdom. 

When they were kids, the prince had begged him over and over to let him up, but true to his orders and his family honor, the alchemist had refused, until he’d given up. Apparently only Kuroo’s family, a long line of talented sorcerers and alchemists had been up there and it was considered their most sacred sanctuary, no matter the crappy conditions. 

After a few moments of tense relative silence, Bokuto turned to his advisor, practically vibrating with unspent energy and worry. 

“He’s been up there for too long,” The flecks had stopped coming out of the tube now and the concoction was now burning so white-hot that it hurt his eyes to look directly at it. 

“Kuroo-san knows what he’s doing, Your Highness,” Akaashi replied, voice steady as ever, but eyes firmly cemented on the place on the ceiling where their friend had vanished up into. 

A few more minutes passed and Bokuto was about to go up there himself, fire and honor be damned when the sound of running liquid stopped him in his tracks. 

He tore his eyes away from the ceiling to look at the pipes fixed above the tube, water had come rushing through them, causing large clouds of steam to rise and loud hissing sounds to echo through the large room. It filled the tube to the brim and flowed over the sides, effectively flushing out the chemical and quenching the flames before they could reach anything else. 

Then, once all of the steam had cleared through the cleverly placed ventilation grilles forged and installed by Kuroo himself, a loud squeak sounded and the flow of water slowed to a meager drip. Under five minutes later the man slid down the main chain and dropped to the floor, a little dusty and with more ash smudged onto his pale arms, but no worse for wear. 

“Damn I really need to fix that,” he mumbled under his breath, flipping his guard up to reveal his face, bangs matted to his face with sweat, but eyes still glittering in their usual hyper way. They always did that after discovering something new, it was one of the only tangible indications of how his brilliant mind would whir with wonder and curiosity. 

He walked up to the tube and his face dimmed a bit, pulling the sword from it.

The strange substance was all gone, revealing the smooth blade but the chemicals hadn’t left it completely as it was before the incident. 

The once clean and plain silvery color had been tinged by the dark red of the bromine to form an almost coppery polish over it. Keeping the reflective properties of the polished steel, but adding the coloring, it managed to look like an almost sunkissed metal. It had a certain glow to it that seemed to fit that idea. 

Kuroo took a rag off of one of the tables and dried it off well as he brought down the shield in front of the two other boys. 

He passed it off to the prince who was inspecting the surface, stone-faced. After passing bottles of metal polish and oil to Akaashi, Kuroo turned to the prince, inclining his head slightly. Bokuto had long since told him that he didn’t ever want to see his friend bowing to him if he could help it. 

“I’m sorry Bo, I didn’t cool it fast enough. I don’t know why it did that, but maybe once it cools down more I can-” A hand was held up, stopping the alchemist in his tracks and deepening his frown.

“Kuroo,” he commanded, making the man’s head snap up to face the royal heir, “Why’re you sorry? You fixed it and made it look cooler!” he was smiling and Kuroo almost sighed in relief at the sight, “It looks like it’s made of solid gold now!” 

“It’s much stronger than some flimsy golden sword,” Kuroo muttered, attempting to sound disgruntled by his sudden change in mood, but the smile tugging at his lips easily gave him away. Akaashi hummed his agreement, an amused look crossing his face before he pivoted to face Bokuto. 

“I hate to interrupt, but Your Highness, we have to go now if you’re going to be presentable in time for dinner,”

“What’s wrong with what I’m wearing now?” Bokuto asked, motioning to his slightly torn and far too casual clothing. His shirt was barely covering his whole torse, being ripped right below his waist. The dip of the neckline had been stretched somehow so that it showed off more skin that could be considered appropriate for a formal dinner and his pants were unraveling a bit at the bottom seams. In response, his advisor looked him up and down, and leveled him with a signature deadpan stare. Kuroo had to turn away and stifle a laugh into his hand at that, pretending to be enraptured with his work when the Prince let out an offended squawk. Akaashi just rolled his eyes, fond, but not backing down. The prince let out a loud, and very dramatic groan, and reluctantly put the sword back into its scabbard at his waist. 

Bokuto looked back to the alchemist and then, with not a trace of hesitance in his movements, he pulled him into a firm embrace. 

Kuroo let out a soft noise of surprise as the prince’s face was suddenly pressed into his shoulder, his spiky hair poking him in the cheek, but he didn’t protest. In fact, he was warm in the already too-hot room, so he should really have been complaining. For some reason, he couldn’t bring himself to do it. The pressure of his skin against his was pleasant in a way that it shouldn’t have been. 

This was the crown prince he was hugging, he needed to stop...whatever it was he was doing and thinking. 

“Thank you for fixing my sword,” He whispered, breath warm against his ear and tone soft and vulnerable. Kuroo felt the hairs on the back of his neck stand at attention as a slight shiver ran through him. 

Before he could say or do anything too stupid in response, Bokuto pulled back, giving him a brilliant smile and then letting go of him. 

“Hey you should come to dinner tonight, I haven’t seen you there in a while and I’m sure mom would love to see you again! They’re making seafood and you can invite Kenma too if you want!” He said, his eyes lighting up as he rambled. The excitement was evident in the twinkle in his eye and the way he was standing completely upright, head held high and voice ringing loud and clear. Kuroo wouldn’t dream of saying no to him, especially when he was like that. So he grinned back. 

“Sure, I wouldn’t miss it, man,” Kuroo said, making the prince perk up even more as he escorted the two higher ups towards the doors. Akaashi went first, walking through the door he was holding with his usual practiced grace. “See you later Akaashi,” He got a nod from the advisor and a final enthusiastic wave from Bokuto before the door closed and they were gone, the doors thudding closed behind them.

Kuroo walked over to one of his tables and leaned heavily onto it with a long-suffering sigh. 

That stupidly hot prince was going to be the death of him and he was partially concerned by the fact that he didn’t really _ mind _ .

Oh well, he had other matters to worry about first, like what he was going to wear, and how the hell he was going to convince Kenma to go to the dinner with him. There was no way he was going into it alone, not with Bokuto all dressed up and smiling at him so dreamily in front of so many important people. No, he would definitely do something stupid like faint on sight, and with no one there to cover for him, there would be a disaster. 

Maybe he could bribe him with some of that sweet pastry that he liked?

**Author's Note:**

> Lol, I wrote this a while ago now and it's just been sitting in my drafts so I figured I'd put this up while I work on the next parts of the Oikage thing I'm doing. Fantasy AUs have always been pretty interesting to me so maybe I'll actually plot one out someday. Idk know about right now tho, I've got a lot in progress atm XD. Thanks for reading!


End file.
